Comparing Soil pH Mapping from Multi-Temporal PlanetScope and Sentinel-2 Data Across Land Use Types

In vegetated areas, soil pH impacts plant growth, soil properties, and spectral characteristics. Remote sensing enables soil pH mapping by delivering detailed surface data, and while high-resolution satellite images show great potential in complex terrains, research in this area is still limited. Th...

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Main Authors: Ziyu Wang, Wei Wu, Hongbin Liu
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Remote Sensing
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Online Access:https://www.mdpi.com/2072-4292/17/2/189
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author Ziyu Wang
Wei Wu
Hongbin Liu
author_facet Ziyu Wang
Wei Wu
Hongbin Liu
author_sort Ziyu Wang
collection DOAJ
description In vegetated areas, soil pH impacts plant growth, soil properties, and spectral characteristics. Remote sensing enables soil pH mapping by delivering detailed surface data, and while high-resolution satellite images show great potential in complex terrains, research in this area is still limited. This study evaluated PlanetScope (high-resolution) and Sentinel-2 (medium-resolution) images in estimating soil pH across diverse land use types in southwestern China’s hilly areas. It examined how spectral variables from four seasonal images affect prediction accuracy. We integrated topographic and spectral variables at seven spatial resolutions (3 m, 10 m, 20 m, 30 m, 40 m, 50 m, and 60 m), using extreme gradient boosting (XGboost) for orchards, dry land, and paddy fields. We found that the models developed with PlanetScope images tended to achieve better prediction accuracy compared to those utilizing Sentinel-2 images. For each satellite, single-temporal images showed greater predictive power under each land use type. In particular, the spring spectral data showed desirable predictive performance for the orchards and the paddy fields, while the autumn spectral data contributed more effectively to the models for the dry land. Specifically, PlanetScope provided the best prediction accuracy for soil pH at 3 m resolution (orchard: <i>R</i><sup>2</sup> = 0.72, <i>MAE</i> = 0.24, <i>RMSE</i> = 0.30, <i>RPD</i> = 1.91; dry land: <i>R</i><sup>2</sup> = 0.77, <i>MAE</i> = 0.37, <i>RMSE</i> = 0.40, <i>RPD</i> = 2.09; paddy field: <i>R</i><sup>2</sup> = 0.66, <i>MAE</i> = 0.35, <i>RMSE</i> = 0.41, <i>RPD</i> = 1.71), while Sentinel-2 performed better at 10 m resolution (orchard: <i>R</i><sup>2</sup> = 0.67, <i>MAE</i> = 0.29, <i>RMSE</i> = 0.33, <i>RPD</i> = 1.75; dry land: <i>R</i><sup>2</sup> = 0.70, <i>MAE</i> = 0.39, <i>RMSE</i> = 0.47, <i>RPD</i> = 1.83; paddy field: <i>R</i><sup>2</sup> = 0.64, <i>MAE</i> = 0.34, <i>RMSE</i> = 0.42, <i>RPD</i> = 1.66). Our findings demonstrate that sensor selection, land use, temporal phases, and modeling resolution significantly impact outputs. High-resolution PlanetScope images prove effective for predicting soil pH in complex terrains.
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spelling doaj-art-7d100e64250b4407a7a485b092fb25132025-01-24T13:47:40ZengMDPI AGRemote Sensing2072-42922025-01-0117218910.3390/rs17020189Comparing Soil pH Mapping from Multi-Temporal PlanetScope and Sentinel-2 Data Across Land Use TypesZiyu Wang0Wei Wu1Hongbin Liu2College of Resources and Environment, Southwest University, Beibei District, Chongqing 400716, ChinaCollege of Computer and Information Science, Southwest University, Beibei District, Chongqing 400716, ChinaCollege of Resources and Environment, Southwest University, Beibei District, Chongqing 400716, ChinaIn vegetated areas, soil pH impacts plant growth, soil properties, and spectral characteristics. Remote sensing enables soil pH mapping by delivering detailed surface data, and while high-resolution satellite images show great potential in complex terrains, research in this area is still limited. This study evaluated PlanetScope (high-resolution) and Sentinel-2 (medium-resolution) images in estimating soil pH across diverse land use types in southwestern China’s hilly areas. It examined how spectral variables from four seasonal images affect prediction accuracy. We integrated topographic and spectral variables at seven spatial resolutions (3 m, 10 m, 20 m, 30 m, 40 m, 50 m, and 60 m), using extreme gradient boosting (XGboost) for orchards, dry land, and paddy fields. We found that the models developed with PlanetScope images tended to achieve better prediction accuracy compared to those utilizing Sentinel-2 images. For each satellite, single-temporal images showed greater predictive power under each land use type. In particular, the spring spectral data showed desirable predictive performance for the orchards and the paddy fields, while the autumn spectral data contributed more effectively to the models for the dry land. Specifically, PlanetScope provided the best prediction accuracy for soil pH at 3 m resolution (orchard: <i>R</i><sup>2</sup> = 0.72, <i>MAE</i> = 0.24, <i>RMSE</i> = 0.30, <i>RPD</i> = 1.91; dry land: <i>R</i><sup>2</sup> = 0.77, <i>MAE</i> = 0.37, <i>RMSE</i> = 0.40, <i>RPD</i> = 2.09; paddy field: <i>R</i><sup>2</sup> = 0.66, <i>MAE</i> = 0.35, <i>RMSE</i> = 0.41, <i>RPD</i> = 1.71), while Sentinel-2 performed better at 10 m resolution (orchard: <i>R</i><sup>2</sup> = 0.67, <i>MAE</i> = 0.29, <i>RMSE</i> = 0.33, <i>RPD</i> = 1.75; dry land: <i>R</i><sup>2</sup> = 0.70, <i>MAE</i> = 0.39, <i>RMSE</i> = 0.47, <i>RPD</i> = 1.83; paddy field: <i>R</i><sup>2</sup> = 0.64, <i>MAE</i> = 0.34, <i>RMSE</i> = 0.42, <i>RPD</i> = 1.66). Our findings demonstrate that sensor selection, land use, temporal phases, and modeling resolution significantly impact outputs. High-resolution PlanetScope images prove effective for predicting soil pH in complex terrains.https://www.mdpi.com/2072-4292/17/2/189hilly topographyextreme gradient boostingdigital soil mappingfeature importancesoil property prediction
spellingShingle Ziyu Wang
Wei Wu
Hongbin Liu
Comparing Soil pH Mapping from Multi-Temporal PlanetScope and Sentinel-2 Data Across Land Use Types
Remote Sensing
hilly topography
extreme gradient boosting
digital soil mapping
feature importance
soil property prediction
title Comparing Soil pH Mapping from Multi-Temporal PlanetScope and Sentinel-2 Data Across Land Use Types
title_full Comparing Soil pH Mapping from Multi-Temporal PlanetScope and Sentinel-2 Data Across Land Use Types
title_fullStr Comparing Soil pH Mapping from Multi-Temporal PlanetScope and Sentinel-2 Data Across Land Use Types
title_full_unstemmed Comparing Soil pH Mapping from Multi-Temporal PlanetScope and Sentinel-2 Data Across Land Use Types
title_short Comparing Soil pH Mapping from Multi-Temporal PlanetScope and Sentinel-2 Data Across Land Use Types
title_sort comparing soil ph mapping from multi temporal planetscope and sentinel 2 data across land use types
topic hilly topography
extreme gradient boosting
digital soil mapping
feature importance
soil property prediction
url https://www.mdpi.com/2072-4292/17/2/189
work_keys_str_mv AT ziyuwang comparingsoilphmappingfrommultitemporalplanetscopeandsentinel2dataacrosslandusetypes
AT weiwu comparingsoilphmappingfrommultitemporalplanetscopeandsentinel2dataacrosslandusetypes
AT hongbinliu comparingsoilphmappingfrommultitemporalplanetscopeandsentinel2dataacrosslandusetypes